class test(object):
    def __init__(self):
        print(self)
class Scr(object):
    def __init__(self):
        self._width=1
        self._height=1

    @property
    def width(self):
        return self._width
    @width.setter
    def width(self, width):
        self._width = width

    @property
    def height(self):
        return self._height
    @height.setter
    def height(self, value):
        self._height = value

    @property
    def res(self):
        return self._height*self._width

t = Scr()
